Construction of BiVO₄/Bi₂WO₆/WO₃ heterojunctions with improved photocatalytic capability in elimination of dye and antibiotics and inactivation of E. coli

Background: Recently, semiconductor photocatalysts have been known as one of most promising strategies for environmental purification and remediation due to the rapid and nonselective oxidation of a broad range of organic pollutants. Methods: In this article, BiVO4/Bi2WO6/WO3 ternary heterojunction with cascade energy band alignment has been proposed and prepared by microwave-assisted hydrothermal reaction. Significant findings: The constructed ternary composite shows a broader absorption spectrum compared with the binary BiVO4/Bi2WO6 and pure BiVO4 samples. In addition, the ternary composite with gradient energy band alignment can accelerate the electron-hole separation and charge carrier transfer leading to decreased photoluminescence (PL) intensity and lifetime. As a result, the BiVO4/Bi2WO6/WO3 heterostructured composite can display higher photocurrent and possess an enhanced performance in the visible-light-driven degradation of methylene blue (MB). Our results indicate that the optimal molar ratio of BiVO4:Bi2WO6:WO3 is found to be 0.375:0.375:0.25, revealing the best photocatalytic activity. The ternary composite with optimal molar ratio exhibits a 50.9% greater degradation rate (rate constant (k) =0.0283 min−1) over the BiVO4 (k = 0.0139 min−1) for the photodegradation of MB. Besides, the resultant ternary system also shows excellent photocatalytic performance in the degradation of antibiotics and antibacterial capability with great biocompatibility.